Field of the Invention
The present disclosure generally relates to a projection apparatus, a method for controlling the same, and a projection system.
Description of the Related Art
In amusement facilities or in flight simulators, for example, simulation systems which employ projection apparatuses can be used all the time for the simulation use recently. One of problems with such projection systems used all the time is how to keep a projecting position, a shape, or image quality of the projected image.
There is a problem that, if the projecting position is shifted due to some factors, such as vibration of the projection apparatus, it may take much time and effort to interrupt the projection and calibrate manually. Especially in a system in which plural projection apparatuses are used in combination, calibration of mutual projecting positions is very difficult, which requires an expert with a special calibration technique.
To solve the above problems, Japanese Patent No. 3908255, for example, discloses a technique to capture a calibration pattern projected by a projection apparatus with a camera, generate an adjustment parameter, and correct a shape of the calibration pattern on a screen. Further, Japanese Patent Laid-Open No. 2011-211693, for example, discloses a technique to prevent a calibration pattern from disturbing the user's viewing the projected image by capturing the calibration pattern projected by non-visible light with a camera.
However, capturing timing of a projected image is not described in Japanese Patent No. 3908255 and Japanese Patent Laid-Open No. 2011-211693. Therefore, in a projection apparatus in which a projected image is updated line sequentially, for example, if the projected image with calibration patterns different for each frame being superimposed is to be captured, patterns of plural frames may exist in a single image depending on capturing timing. There is a problem that no appropriate adjustment parameter can be obtained from such an image.
This problem will be described with reference to FIGS. 12A to 12D. FIG. 12A illustrates exemplary update timing of an image drawn on a panel of a projection apparatus. FIG. 12B illustrates a projected image of a frame 1, and FIG. 12C illustrates a projected image of a subsequent frame 2.
The panel which displays the projected image updates the drawn image for each line in synchronization with a horizontal synchronizing signal (HD). An image of a 1st line of the frame 1 is drawn between time t121 to t122. An image of a 2nd line of the frame 1 is drawn between time t122 to t123. Similarly, all of the lines (here, N lines) of the panel are updated sequentially. The image of the line for which update is terminated is held until the next update.
FIG. 12D illustrates an image drawn on the panel at time t124. At time t124, a part up to a kth line which corresponds to ⅓ of the image of the frame 2 has been updated, and The image of the frame 1 is drawn continuously from a (k+1)th line to an Nth line. If the projected image is captured at this timing, an image as illustrated in FIG. 12D in which the frames 1 and 2 are mixed is captured. Using this image for the correction of the projected image can cause erroneous correction.